If there's a cost associated with having it attack, the player isn't forced to pay that cost, so it doesn't have to attack in that case either
It's true, giving your opponent a land is likely to be much more impactful than giving them some life
Assaultron Dominator can turn your energy counters into solid combat keyword counters for aggressive attacks
For those who havent played with this iconic necromancer, Liliana is a strong card because if you build your deck properly you can break its symmetry through discarding recursive threats, cards with flashback, or things that will later be reanimated
The cards effect is great too they either get forced into giving you a card from their hand or a permanent on the battlefield
Namely, when you play a Battle card in its Siege form, youre not the one protecting it